As many as a sixth of England's teenagers could be taking new, vocational exams in future, the education secretary thinks.

At present some 50,000 of the 1.2 million 15 year olds take vocational courses each year.

David Blunkett has said that more skills-based study might appeal to "three or four times that number".

"We must make sure they have that chance," he said in a speech to the Institute for Public Policy Research.

"Vocational GCSEs and Modern Apprenticeships offer the right qualifications structure to enable it to happen."

Teachers' hours

Mr Blunkett announced in January a programme to expand significantly the vocational opportunities available for 14 to 16 year olds.

This included the launch of Vocational GCSEs in a range of subjects in September 2002, extra money for up to 40,000 vocational placements a year in further education, and the idea of giving more time for vocational study within the national curriculum.

In his wide-ranging speech, Mr Blunkett restated the government's opposition to putting a limit on teachers' working hours.

He was due to meet teachers' unions later on Tuesday to discuss the scope of an independent inquiry into teachers' workload.

The three biggest unions passed a joint resolution at their Easter conferences, threatening industrial action in pursuit of a 35-hour week if they were not happy with the scope of the inquiry.

But Mr Blunkett told his audience at the institute that "prescribed maximum teaching hours are clearly a red herring" - although it should be possible to give teachers more help in the classroom and with paperwork, he said.

More assistants

He said the numbers of classroom and administrative assistants in schools had increased dramatically since 1997.

Provisional figures from January show there were 44,000 more support staff in primary and secondary schools, with half of that increase in the last year - a much bigger rise than the government's target.

The leader of the biggest classroom union, the NUT, said more help was welcome but teachers still had to guide, manage and advise assistants.

"It would be wrong for the government to imply that this is the answer to the excessive workload faced by teachers and the current crisis in teacher supply," Doug McAvoy said.

Mr Blunkett also suggested that his successor if Labour won the general election - Mr Blunkett himself is widely expected to move to the Home Office - would give state schools greater freedom.

"However, in doing so, we must never lose the gains in accountability that have been made," he added.

He made it clear that school performance tables were here to stay. They have been abolished in Northern Ireland and are under review in Wales.

Six-yearly school inspections

And he discounted the idea that schools might be inspected by Ofsted less frequently.

The inspectorate's new chief, Mike Tomlinson, has promised there will be a complete review of the way it operates, after the election.

A senior official in the NASUWT classroom union, Martin Johnson, has said that among the ideas being floated by Ofsted is a 10-year inspection cycle. At present schools are inspected every six years.

But Mr Blunkett said: "I am sure it would be a mistake to change the frequency of inspections.

"Six years seems about right to me - and broadly reflects the school career of a youngster in primary or secondary school - and I know that Mike Tomlinson strongly agrees with me on this."

The leader of the National Association of Head Teachers, David Hart, said: "In what suspiciously looks like the secretary of state's farewell speech before the forthcoming election, he has confirmed that raising standards depends on successful headteachers and their staffs, not upon prescriptive government edict.

"We sincerely hope that this means we shall see less of the 'nanny state' and more policy based on trust after 7 June."